Abstract: A two-scale approach to the diffuse light scattering from rough surfaces is proposed and applied for the first time. On the microscopic scale, the inter- and intra-layer contributions to the complex optical conductivity tensor are quantum mechanically calculated ab initio, based on the Luttinger formalism and by means of a contour integration within the spin-polarized relativistic screened Korringa–Kohn–Rostoker bandstructure method. These contributions are then properly gathered to determine the layer-resolved permittivities, which in turn uniquely characterize, from an optical point of view, the complete surfaced system of interest and hence yield, together with the known roughness of the surface, the set-up of the next, macroscopic part of the proposed approach. On the latter length scale, the previously developed 2 × 2 matrix technique, which properly accounts for all possible reflections and optical interferences within a layered system, is carefully generalized to also account for the roughness of the surface layer. Applied to a semi-infinite bcc Fe/Fe(100) tribological sample, this two-scale approach has shown that the pointwise normal refraction vector of the rough surface layer, e.g., closely follows the inverse magnitude of the surface normal, at least for linearly polarized light and normal incidence.
Abstract: In this work, a comparison of three different methods for analysing topographies and roughness on machined metal surfaces is presented. To obtain comparable results, the measurements were done on one and the same set of samples. For this purpose, an atomic force microscope (AFM), a confocal white light microscope, and a scattering light system were used to analyse the topography of samples of the same material, but with the topographies occurring step by step from the grinding process to the polishing process. Based on the results of the investigations with the parametric system (scattering light sensor) and the profilometric systems (AFM, confocal white light microscope), we established a correlation between the roughness parameters and the scattering light parameter. It is shown that the different methods lead to different roughness parameters of the same surface.
Abstract: This paper discusses a promising method to investigate defects on high-gloss finished metal surfaces. The main aim is to detect very shallow scratches on such tribological surfaces. The method must be simple in its applicability, insensitive to external disturbances, and sufficiently fast for application in monitoring industrial processes. To achieve this, the principle of light scattering is used by scanning a surface with a compact scattering light sensor using a red LED as a light source. The reflected light is scattered into a specular part and a diffuse part, and collected by a one-dimensional CCD-array. The detected intensity distribution of the scattered light depends on the topography of the reflecting surface. Significant variations in the intensity profile will permit to identify the surface defects. With this system we were able to detect scratches on high-gloss metal sheets with a typical width of 1 μm and a depth as small as 40 nm. The geometrical dimensions of these shallow scratches have been determined with a confocal white light microscope.
Abstract: This paper discusses a promising method to investigate high gloss finished metal surfaces. The main aim is to detect very shallow scratches on such surfaces. The method must be simple in its applicability, insensitive to external disturbances and sufficiently fast for application in monitoring industrial processes. To achieve this, the principle of light scattering is used by scanning a surface with a compact scattering light sensor using an LED as a light source ( = 632.8nm). The reflected light is scattered into a specular part and a diffuse part, and collected by a one dimensional CCD-Array. The detected intensity distribution of the scattered light depends on the topography of the reflecting surface. Significant variations in the intensity profile will permit to identify the surface defects. With this system we were able to detect scratches on high gloss metal sheets with a typical width of 1 µm and a depth as small as 40 nm.
